For \(\mu >1\) , it is well-known (see e.g. [1]}, [2]}, [3]}) that the wave operators
\(W_\pm =W_\pm (H,\Delta ^2) :=\operatornamewithlimits{s-lim}_{t\rightarrow \pm \infty }e^{itH}e^{-it\Delta ^2}\) 
